<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .outter {
            width: 400px;
            height: 300px;
            background-color: skyblue;
            position: relative;
        }

        .box {
            width: 100px;
            height: 100px;
        }

        .box1 {
            background-color: blue;
        }

        .box2 {
            background-color: rgb(206, 46, 148);
            position: absolute;
        }

        .box3 {
            background-color: antiquewhite;
        }

        /* 要求 当鼠标移动到outter当中的时候 显示box3  并且将box2右边移动*/
        .outter:hover .box2 {
             left: 100px;
        }
    </style>
</head>
<body>
    <div class="outter">
        <div class="box box1">盒子1</div>
        <div class="box box2">盒子2</div>
        <div class="box box3">盒子3</div>
    </div>
</body>
</html>